Many Email::Store plugins will munge the underlying rfc2822 representation of the message,
which in some cases is undesirable.

When in use Email::Store::Pristine stores a copy of the original message in a pristine_copies relationship.
This is a one-to-many relationship as in the case of a cross-posted mail you may recieve many subtly different versions of the same mail,
for which there will be only one Email::Store::Mail message due to the unchanging Message-ID.

A pristine_copies accessor is added to the Email::Store::Mail object,
which returns Email::Store::Pristine copies which encapsulate the original message.